Not really. Logically, since they have been making them for a while, Apple can reap more profits out of selling an iPhone 4 now than they will with an iPhone 5 at launch, since that newer hardware will be more expensive but will still have to be sold at the same price point (give or take).

Apple might simply release a white iPhone 4 because of the fact that the iPhone 4 line will be replacing the 3GS as the 'cheap models, so might as well have a little diversity to suit different tastes.

from what I remember Apple takes the phones that are returned and uses the memory and a few other pieces for making the latest phone

ie: 3GS gets returned, they use some of the parts to make the iPhone4.

example: When iPhone4 came out in 16GB and 32GB, the CDN providers stopped selling 16GB and 32GB 3GS iPhones. They started selling 8GB 3GS iphones which were made from 3G returns.

Same thing will happen with the iPhone4. We will be getting an iPhone4 8GB when the iPhone5 comes out